Mechanism(s) located in the limiting cellular layers of the cornea, and particularly the endothelium, that contribute to stromal dehydration, and hence light transparency of the tissue are under investigation. Research is focused on naturally occurring disulfide compounds with a demonstrated capacity to effect transendothelial fluid transport as measured by biochemical and physiological parameters. Suitable derivatives of such compounds as cystine or glutathione are being used to discriminate hormone-like effects mediated by interaction with the cell membrane and intracellular metabolic events. The role of sulfhydryl groups in effecting molecular changes that diminish in vitro water solubility of lenticular proteins during aging and cataract development is under study. Low molecular weight components released by various reductive agents appear to be involved and methods to isolate and identify these products are being explored.